header{
    display: flex;
    justify-content: center;
    align-items: center;
}

nav{
    flex-grow: 1;
}


nav ul{

    list-style-type: none;
    margin: 0;
    padding: 0;
    overflow: hidden;
    background-color: white;

}

nav ul li{
    float: left;
}

nav ul li a{
    display: block;
    color: black;
    text-align: center;
    padding: 16px;
    text-decoration: none;
}


nav ul li:hover{
    background-color: gray;
}